An alternative determination of transverse shear stiffnesses for sandwich and laminated plates

Two-dimensional shear-deformable laminated plate theories can be classi®ed as equivalent single-layer theories and layerwise theories. Layerwise theories lead to better approximations than equivalent single-layer theories, but the large number of independent unknowns in these theories requires more computational power in comparison with calculations, based on equivalent single-layer theories. The quality of any equivalent single-layer theory based calculation is in¯uenced by the correct determination of the e€ective sti€nesses. Many theories result in identical sti€nesses for bending, tension/compression, in-plane shear and torsion. The di€erences between the approaches are connected with the transverse shear sti€nesses. The method of determination of the transverse shear sti€nesses proposed here leads to expressions which depend on the solution of a Sturm±Liouville-problem. For special cases, the sti€nesses are calculated and compared with results from other authors. It can be shown that the present approach can be useful not only in the case of laminated plates, but also for sandwich plates.